Display panel

ABSTRACT

A display panel can include a substrate including first, second and third subpixels; an overcoat layer including a first inclined surface in at least one of the first, second and third subpixels; first, second and third anode electrodes corresponding to the first, second and third subpixels, respectively, wherein at least one of the first, second and third anode electrodes includes a second inclined surface overlapping with the first inclined surface of the overcoat layer; first, second and third organic light emitting layers disposed on the first, second and third anode electrodes, respectively; and a bank layer disposed on the overcoat layer, the bank layer including a third inclined surface overlapping with both the first and second inclined surfaces of the overcoat layer and the at least one of the first, second and third anode electrodes, in which at least one of the first, second and third inclined surfaces is configured to reflect light emitted from a corresponding one of the first, second and third organic light emitting layers.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Republic of Korea PatentApplication No. 10-2018-0163604, filed in the Republic of Korea on Dec.17, 2018, the disclosure of which is incorporated herein by reference inits entirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to a display panel and a display deviceincluding the same.

Description of the Background

Since the advent of the information society, there have been growingneeds for various display panels for using in display devices, lightingdevices, or the like. Among various types of display panels, an organiclight emitting display panel is advantageous in a reduction in overallweight and thickness, since an additional backlight source is notrequired. As a result, demands for organic light emitting display panelshave increased steadily.

However, when the organic light emitting display panel including anorganic light emitting layer emitting light is operated, there is aproblem that a light extraction efficiency of the organic light emittingdisplay panel is lowered and corresponding luminance efficiency islowered because some of the light emitted from the organic lightemitting layer cannot be emitted outside the organic light emittingdisplay panel, and therefore trapped inside the organic light emittingdisplay device.

In addition, much research is being carried out to solve a problem thatcauses an image distortion according to angles of view of the displaypanel.

SUMMARY

To address these issues, at least one object of the present disclosureis to provide a display panel and a display device with enhancedluminance efficiency.

It is at least one object of the present disclosure to provide a displaypanel and a display device with a reduced color shift for differentviewing angles.

In accordance with an aspect of the present disclosure, a display panelincludes a substrate, an overcoat layer, a first anode electrode, asecond anode electrode, a third anode electrode, a bank layer, a firstorganic light emitting layer, a second organic light emitting layer, athird organic light emitting layer, and a cathode electrode.

The substrate can be subdivided into areas corresponding to a firstsubpixel, a second subpixel and a third subpixel.

The first subpixel emits visible light of a first color, the secondsubpixel emits visible light of a second color, and the third subpixelemits visible light of a third color. Each of the first, second andthird colors can be different from one another.

The overcoat layer can be located over the substrate, and include aconvex area and a concave area, which are connected to each otherthrough an inclined area.

The inclined area can include a first inclined surface surrounding theconcave area in at least one of the first, second and third subpixels.

The first anode electrode can be located over the overcoat layer, formedalong with a surface of the overcoat layer, and located in the firstsubpixel.

The second anode electrode can be located over the overcoat layer,formed along with the surface of the overcoat layer, and located in thesecond subpixel.

The third anode electrode can be located over the overcoat layer, formedalong with the surface of the overcoat layer, and located in the thirdsubpixel.

The bank layer includes an open area located in the center area of eachof the first, second and third subpixels, and can be located on theovercoat layer and the first, second and third anode electrodes.

The first organic light emitting layer can be located on a part of thefirst anode electrode located in the open area of the bank layer.

The second organic light emitting layer can be located on a part of thesecond anode electrode located in the open area of the bank layer.

The third organic light emitting layer can be located on a part of thethird anode electrode located in the open area of the bank layer.

The cathode electrode can be located on the first, second and thirdorganic light emitting layers and the bank layer.

At least one of the first, second and third anode electrodes can includea second inclined surface formed along with the first inclined surface.

The bank layer can include a third inclined surface formed along withthe second inclined surface.

An angle of the first inclined surface to the concave area can begreater than or equal to 27°.

A distance between the second inclined surface and third inclinedsurface is less than or equal to 3.2 μm.

A height of the first inclined surface can be greater than or equal to0.7 μm.

The display panel can include two types of areas, which include anopening area corresponding to the open area of the bank layer and anon-opening area corresponding to a remaining area except for the openarea of the bank layer.

When an organic light emitting layer in a subpixel including the firstinclined surface emits light, the display panel can include a firstlight emitting area and a second light emitting area.

Visible light is emitted from the first light emitting area. The firstlight emitting area can have a shape corresponding to a shape of theopening area.

The second light emitting area does not overlap the first light emittingarea. The second light emitting area can have a shape corresponding to ashape of an edge of the first light emitting area.

The second light emitting area can surround the first light emittingarea.

The second light emitting area can be located in the non-opening area.

Color coordinates of visible light emitted from the first light emittingarea can be different from color coordinates of visible light emittedfrom the second light emitting area adjacent to the first light emittingarea.

At least one of the first, second and third organic light emittinglayers can extend to a portion of the bank layer.

In the at least one of the first, second and third organic lightemitting layers extending to the portion of the bank layer, a portionformed on the anode electrode can be thicker than a portion formed onthe third inclined surface of the bank layer.

The incline area can include the first inclined surface surrounding theconcave area in at least one of the first subpixel and the secondsubpixel.

The visible light of the first color can be a red visible light having awavelength of 595 nm to 740 nm.

The visible light of the second color may be a green visible lighthaving a wavelength of 495 nm to 595 nm.

The visible light of the third color can be a blue visible light havinga wavelength of 450 nm to 495 nm.

The overcoat layer can include the first inclined surface in at leasttwo of the first, second and third subpixels, and an angle of the firstinclined surface included in each of the first, second and thirdsubpixels can be different from one another, and a distance between thesecond inclined surface and the third inclined surface in each of thefirst, second and third subpixels can be different from one another.

The overcoat layer can include the first inclined surface in at leasttwo of the first, second and third subpixels, and a height of the firstinclined surface included in each of the first, second and thirdsubpixels can be different from one another.

In accordance with embodiments of the present disclosure, the anodeelectrode can be formed of the inclined surface, and as a result, it ispossible to provide a display panel with high luminous efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically illustrating a configuration ofa display device according to embodiments of the present disclosure.

FIG. 2 is a view schematically illustrating a system implementation ofthe display device according to embodiments of the present disclosure.

FIG. 3 is a view illustrating a structure of a subpixel in a situationwhere the display panel is configured with an organic light emittingdiode (OLED) panel according to embodiments of the present disclosure.

FIG. 4 is a cross-sectional view illustrating the display deviceaccording to embodiments of the present disclosure.

FIG. 5 is a view illustrating that light emitted from any subpixel ofthe display panel is reflected from a second inclined surface accordingto embodiments of the present disclosure.

FIG. 6 is an enlarged cross-sectional view illustrating a part of thesubpixel shown in FIG. 5 according to embodiments of the presentdisclosure.

FIGS. 7A and 7B illustrate the display panel including an opening area,a non-opening area, a first light emitting area, and a second lightemitting area according to embodiments of the present disclosure.

FIG. 8 is a view illustrating how light emitted from a subpixel of thedisplay panel travels according to embodiments of the presentdisclosure.

FIG. 9 is a cross-sectional view illustrating the display deviceaccording to embodiments of the present disclosure.

FIG. 10 is an enlarged cross-sectional view illustrating a part of thedisplay device shown in FIG. 9 according to embodiments of the presentdisclosure.

FIGS. 11(a)-(d) and 12(a)-(d) are views illustrating a degree ofdegradation of display quality of images according to different viewingangles of the display panel according to embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Hereinafter, example embodiments of the disclosure will be described indetail with reference to the accompanying drawings. In denoting elementsof the drawings by reference numerals, the same elements will bereferenced by the same reference numerals although the elements areillustrated in different drawings. Further, in the following descriptionof the disclosure, detailed description of known functions andconfigurations incorporated herein may be omitted when it may make thesubject matter of the disclosure rather unclear.

Terms, such as first, second, A, B, (a), or (b) may be used herein todescribe elements of the disclosure. Each of the terms is not used todefine essence, order, sequence, or number of an element, but is usedmerely to distinguish the corresponding element from another element.When it is mentioned that an element is “connected” or “coupled” toanother element, it should be interpreted that another element may be“interposed” between the elements or the elements may be “connected” or“coupled” to each other via another element as well as that one elementis directly connected or coupled to another element. When it isdescribed that an element is “located,” “disposed,” “arranged,”“formed,” or the like over another element, it should be interpretedthat not only the element is directly contacted on the another element,but further another element may be “interposed” between the element andthe another element.

FIG. 1 is a block diagram schematically illustrating a configuration ofa display device according to embodiments of the present disclosure.

The display device according to embodiments of the present disclosurecan be a display device with a display panel, or can further include orbe included in a lighting device/apparatus/system, a luminescencedevice/apparatus/system, or the like. Hereinafter, for convenience ofdescription and ease of understanding, discussions are conducted basedon the display device with the display panel. However, the followingdescription may be applicable to equivalently or similarly to variousdevices/apparatuses/systems with functionalities for displaying images,such as, the lighting device/apparatus/system, the luminescencedevice/apparatus/system, or the like.

In accordance with embodiments of the present disclosure, the displaydevice can include a panel (PNL) for displaying images or outputtinglight, and a driving circuit (or a driver) for driving the panel (PNL).

The panel (PNL) can include a plurality of data lines (DL) and aplurality of gate lines (GL), and include a plurality of subpixels (SP)that is defined by the plurality of data lines (DL) and the plurality ofgate lines (GL) and that is arranged in a matrix pattern.

The plurality of data lines (DL) and the plurality of gate lines (GL)can be arranged to intersect each other in the panel (PNL). For example,the plurality of gate lines (GL) can be arranged in a first direction oron one of a row or a column, and the plurality of data lines (DL) can bearranged in a second direction or on the other of the row or the column.Hereinafter, for convenience of description and ease of understanding,it may be considered that the plurality of gate lines (GL) is arrangedon one or more rows and the plurality of data lines (DL) is arranged onone or more columns.

The panel (PNL) can include other types of signal lines other than theplurality of data lines (DL) and the plurality of gate lines (GL)according to a structure of a subpixel, etc. For example, the displaypanel can further include at least one driving voltage line, at leastone reference voltage line, at least one common voltage line, or thelike.

The panel (PNL) can be various types of panel, such as, a liquid crystaldisplay (LCD) panel, an organic light emitting diode (OLED) panel, orthe like.

For example, different types of signal lines can be disposed in thepanel (PNL) depending on a structure of subpixels, a type of panel(e.g., an LCD panel, an OLED panel, etc.), or the like. In the presentdisclosure, the signal line may denote a term including an electrode towhich a signal is applied.

The panel PNL can include an active area (A/A) displaying an image and anon-active area (N/A) not displaying an image and located in an edgearea. Here, the non-active area (N/A) can be referred to as a bezel areaor the edge area of the panel or the display device.

A plurality of subpixels (SP) is arranged in the active area (A/A) fordisplaying images.

At least one pad, such as a conductive trace, electrically connected toa data driver (DDR) is disposed in the non-active area (N/A), and aplurality of data link lines can be disposed in the non-active area(N/A) for electrically connecting the pad to the plurality of data lines(DL). In this situation, the plurality of data link lines can be a partof the plurality of data lines (DL) extending to the non-active area(N/A), or be separate patterns electrically connected to the pluralityof data lines (DL).

In addition, the non-active area (N/A) further can includegate-driving-related lines for delivering a voltage (signal) for drivingat least one gate of at least one transistor for driving at least onesubpixel from the pad electrically connected to the data driver (DDR) toa gate driver (GDR). For example, the gate-driving-related lines caninclude clock lines for delivering clock signals, gate voltage lines fordelivering gate voltages (VGH, VGL), gate driving control signal linesfor delivering various control signals for generating scan signals, orthe like. The gate-driving-related lines are arranged in the non-activearea (N/A), unlike gate lines (GL) arranged in the active area (A/A).

The driving circuit can include the data driver (DDR) for driving theplurality of data lines (DL), the gate driver (GDR) for driving theplurality of gate lines (GL), and a controller (CTR) for controlling thedata driver (DDR) and the gate driver (GDR).

The data driver (DDR) can drive the plurality of data lines (DL) byoutputting data voltages to the plurality of data lines (DL).

The gate driver (GDR) can drive the plurality of gate lines (GL) byoutputting scan signals to the plurality of gate lines (GL).

The controller (CTR) can provide various control signals (DCS), (GCS)for driving and/or operating the data driver (DDR) and the gate driver(GDR), and control the driving and/or operating of the data driver (DDR)and the gate driver (GDR). In addition, the controller (CTR) can provideimage data (DATA) to the data driver (DDR).

The controller (CTR) starts scanning operation according to timingprocessed in each frame, converts image data input from other devices orimage providing sources to a data signal form used in the data driver(DDR) and then outputs image data (DATA) resulted from the converting,and controls the driving of at least one data line at a pre-configuredtime aligned with the scanning operation.

In order to control the data driver (DDR) and the gate driver (GDR), thecontroller (CTR) receives a timing signal, such as, a verticalsynchronous signal (Vsync), a horizontal synchronous signal (Hsync), aninput data enable (DE) signal, a clock signal (CLK), or the like, fromother devices or image providing sources, such as, a host system, andgenerates various control signals and outputs the generated signals tothe data driver (DDR) and the gate driver (GDR).

For example, to control the gate driver (GDR), the controller (CTR)outputs various gate control signals (GCS) including a gate start pulse(GSP), a gate shift clock (GSC), a gate output enable (GOE) signal, orthe like.

In addition, to control data driver (DDR), the controller (CTR) outputsvarious data control signals (DCS) including a source start pulse (SSP),a source sampling clock (SSC), a source output enable (SOE) signal, orthe like.

The controller (CTR) can be a timing controller used in the typicaldisplay technology or a control apparatus/device capable of additionallyperforming other control functionalities in addition to the typicalfunction of the timing controller.

The controller (CTR) can be implemented as a separate unit from the datadriver (DDR), or integrated with the data driver (DDR) and implementedas an integrated circuit.

The data driver (DDR) receives image data (DATA) from the controller(CTR), and provides data voltages to the plurality of data lines (DL).Thus, the data driver (DDR) drives the plurality of data lines (DL).Herein, the data driver (DDR) may also be referred to as a “sourcedriver.”

The data driver (DDR) can transmit various signals to and/or receivethem from the controller (CTR) through various interfaces.

The gate driver (GDR) sequentially drives the plurality of gate lines(GL) by sequentially providing scan signals to the plurality of gatelines (GL). Herein, the gate driver (GDR) may also be referred to as a“scan driver.”

According to controlling of the controller (CTR), the gate driver (GDR)sequentially provide a scan signal, such as an on-voltage or anoff-voltage to the plurality of gate lines (GL).

When a specific gate line is asserted by a scan signal from the gatedriver (GDR), the data driver (DDR) converts image data (DATA) receivedfrom the controller into analog data voltages and provides the resultedanalog data voltages to the plurality of data lines (DL).

The data driver (DDR) can be located on, but not limited to, only oneside (e.g., an upper side or a lower side) of the panel (PNL), or insome embodiments, be located on, but not limited to, two sides (e.g., anupper side and a lower side) of the panel (PNL) according to drivingschemes, panel design schemes, or the like.

The gate driver (GDR) can be located on, but not limited to, only oneside (e.g., a left side or a right side) of the panel (PNL), or in someembodiments, be located on, but not limited to, two sides (e.g., a leftside and a right side) of the panel (PNL) according to driving schemes,panel design schemes, or the like.

The data driver (DDR) can be implemented by including one or more sourcedriver integrated circuits (SDIC).

Each source driver integrated circuit (SDIC) can include a shiftregister, a latch circuit, a digital to analog converter (DAC), anoutput buffer, or the like. In some embodiments, the data driver (DDR)can further include one or more analog to digital converters (ADC).

Each source driver integrated circuit (SDIC) can be connected to thepad, such as a bonding pad, of the panel (PNL) in a tape automatedbonding (TAB) type or a chip on glass (COG) type, or be directlydisposed on the panel (PNL). In some instances, each source driverintegrated circuit (SDIC) can be integrated and disposed on the panel(PNL). In addition, each source driver integrated circuit (SDIC) can beimplemented in a chip on film (COF) type. In this case, each sourcedriver integrated circuit (SDIC) can be mounted on a circuit film andelectrically connected to the data lines (DL) arranged in the panel(PNL) through the circuit film.

The gate driver (GDR) can include a plurality of gate driving circuits(GDC). Herein, the plurality of gate driving circuits (GDC) each cancorrespond to the respective plurality of gate lines (GL).

Each gate driving circuit (GDC) can include a shift register, a levelshifter, and the like.

Each gate driving circuit (GDC) can be connected to the pad, such as abonding pad, of the panel (PNL) in a tape automated bonding (TAB) typeor a chip on glass (COG) type. In addition, each gate driving circuit(GDC) can be implemented in a chip on film (COF) type. In thissituation, each gate driving circuit (GDC) can be mounted on a circuitfilm and electrically connected to the gate lines (GL) arranged in thepanel (PNL) through the circuit film. In addition, each gate drivingcircuit (GDC) may be integrated into the panel (PNL) in a gate in panel(GIP) type. That is, each gate driving circuit (GDC) may be directlyformed in the panel (PNL).

FIG. 2 is a view illustrating a structure of a subpixel, in which thedisplay panel is configured with an organic light emitting diode (OLED)panel according to embodiments of the present disclosure.

Referring to FIG. 2, each subpixel (SP) in a panel, such as the OLEDpanel 110, can be implemented by electronic elements including, but notlimited to, an organic light emitting diode (OLED), a driving transistor(DRT) for driving the organic light emitting diode (OLED), a switchingtransistor (O-SWT) electrically connected between a first node (N1) ofthe driving transistor (DRT) and a corresponding data line (DL), astorage capacitor (Cst) electrically connected between the first node(N1) and a second node (N2) of the driving transistor (DRT), or thelike.

The organic light emitting diode (OLED) can include an anode electrode,an organic light emitting layer, a cathode electrode, and the like.

FIG. 2 is a view schematically illustrating a system implementation ofthe display device according to embodiments of the present disclosure.

Referring to FIG. 2, in a display device according to embodiments of thepresent disclosure, a data driver (DDR) may be implemented in the chipon film (COF) type of various types, such as, the TAB, the COG, the COF,the GIP, or the like. Also, a gate driver (GDR) may be implemented inthe gate in panel (GIP) type of various types, such as, the TAB, theCOG, the COF, the GIP, or the like.

The data driver (DDR) can be implemented as one or more source driverintegrated circuits (SDIC). FIG. 2 shows an embodiment in which the datadriver (DDR) is implemented as a plurality of source driving integratedcircuits (SDIC).

When the data driver (DDR) is implemented in the COF type, each sourcedriving integrated circuit (SDIC) served as the data driver (DDR) can bemounted on a source side circuit film (SF).

One side of the source side circuit film (SF) can be electricallyconnected to the pad, such as an array of pads, disposed in thenon-active area (N/A).

At least one line electrically connecting between the source drivingintegrated circuit (SDIC) and the panel (PNL) can be arranged on thesource side circuit film (SF).

For circuit connections between the plurality of source drivingintegrated circuits (SDIC) and other units or electronic elements, thedisplay device can include at least one source printed circuit board(SPCB), and a control printed circuit board (CPCB) for mounting severalunits used for controlling the display device and otherelements/units/devices.

The other side of the source side circuit film (SF), in which the sourcedriving integrated circuit (SDIC) is mounted, can be connected to the atleast one source printed circuit board (SPCB).

That is, the one side and the other side of the source side circuit film(SF) in which the source driving integrated circuit (SDIC) is mountedcan be electrically connected to the non-active area (N/A) of the panel(PNL) and the at least one source printed circuit board (SPCB),respectively.

The controller (CTR) for controlling the data driver (DDR), the gatedriver (GDR), or the like can be disposed on the control printed circuitboard (CPCB).

In addition, the control printed circuit board (CPCB) can furtherinclude a power management integrated circuit (PMIC) that providesvarious voltages or currents or controls various voltages or currents tobe provided, to the panel (PNL), the data driver (DDR), the gate driver(GDR), and the like.

The source printed circuit board (SPCB) and the control printed circuitboard (CPCB) can be connected to each other in a circuit through atleast one connection unit (CBL). Here, the connection unit (CBL) can bea flexible printed circuit (FPC), a flexible flat cable, or the like.

At least one source printed circuit board (SPCB) and the control printedcircuit board (CPCB) can be integrated into one printed circuit board.

When the gate driver (GDR) is implemented in the gate in panel (GIP)type, a plurality of gate driving circuits (GDC) included in the gatedriver (GDR) can be directly formed in the non-active area (N/A) of thepanel (PNL).

Each of the plurality of gate driving circuits (GDC) can output scansignals to corresponding gate lines arranged in the active area (A/A) ofthe panel (PNL).

The plurality of gate driving circuits (GDC) arranged in the panel (PNL)can receive various signals (a clock signal, a high level gate voltage(VGH), a low level gate voltage (VGL), a start signal (VST), a resetsignal (RST), or the like) for generating the scan signals throughgate-driving-related lines disposed in the non-active area (N/A).

The gate-driving-related lines disposed in the non-active area (N/A) canbe electrically connected to the source side circuit film (SF) disposedclosest to a plurality of gate driving circuits (GDC).

FIG. 3 is a view illustrating a structure of a subpixel, in which thedisplay panel is configured with an organic light emitting diode (OLED)panel, according to embodiments of the present disclosure.

Referring to FIG. 3, each subpixel SP in the panel 110, such as the OLEDpanel, can be implemented by electronic elements including, but notlimited to, an organic light emitting diode (OLED), a driving transistor(DRT) for driving the organic light emitting diode (OLED), a switchingtransistor (O-SWT) electrically connected between a first node (N1) ofthe driving transistor (DRT) and a corresponding data line (DL), astorage capacitor (Cst) electrically connected between the first node(N1) and a second node (N2) of the driving transistor (DRT), or thelike.

The organic light emitting diode (OLED) can include an anode electrode,an organic light emitting layer, a cathode electrode, and the like.

Referring to FIG. 3, an anode electrode (also referred to as a pixelelectrode) of the organic light emitting diode (OLED) can beelectrically connected to a second node (N2) of a driving transistor(DRT). A low voltage (EVSS) can be applied to a cathode electrode (alsoreferred to as a common electrode) of the organic light emitting diode(OLED).

Herein, the low voltage (EVSS) can be a ground voltage or a voltagehigher or lower than the ground voltage. In addition, a value of the lowvoltage (EVSS) can be varied depending on a driving state. For example,values of low voltage (EVSS) when image driving is performed and whensensing driving is performed can be differently set from each other.

The driving transistor (DRT) drives the organic light emitting diode(OLED) by providing driving currents to the organic light emitting diode(OLED).

The driving transistor (DRT) can include a first node (N1), a secondnode (N2) a third node (N3), and the like.

The first node (N1) of the driving transistor (DRT) can be a gate node,and can be electrically connected to a source node or a drain node ofthe switching transistor (O-SWT). The second node (N2) of the drivingtransistor (DRT) can be a source node or a drain node, and electricallyconnected to the anode electrode (or cathode electrode) of the organiclight emitting diode (OLED). The third node (N3) of the drivingtransistor (DRT) can be the drain node or the source node. A drivingvoltage (EVDD) can be applied to the third node (N3) that can beelectrically connected to a driving voltage line (DVL) providing thedriving voltage (EVDD).

The storage capacitor (Cst) can be electrically connected between thefirst node (N1) and the second node (N2) of the driving transistor (DRT)and can maintain a data voltage (Vdata) corresponding to an image signalvoltage or a corresponding voltage for one frame time (or apre-configured time).

The drain node or the source node of the switching transistor (O-SWT) iselectrically connected to a corresponding data line, and the source nodeor the drain node of the switching transistor (O-SWT) is electricallyconnected to the first node (N1) of the driving transistor (DRT), andthe gate node of the switching transistor (O-SWT) is electricallyconnected to a corresponding gate line, and thereby can receive scansignal (SCAN).

On-off operation of the switching transistor (O-SWT) may be controlledby a scan signal (SCAN) input to the gate node of the switchingtransistor (O-SWT) through a corresponding gate line.

The switching transistor (O-SWT) can be turned on by the scan signal(SCAN), may transfer a data voltage (Vdata) provided from acorresponding data line (DL) to the first node (N1) of the drivingtransistor (DRT).

In addition, the storage capacitor (Cst) can be an external capacitorconfigured to be located on outside of the driving transistor (DRT)other than an internal capacitor, that is, a parasitic capacitor (e.g.,a Cgs, a Cgd), that presents between the first node (N1) and the secondnode (N2) of the driving transistor (DRT).

Each of the driving transistor (DRT) and the switching transistor(O-SWT) may be an n-type transistor or a p-type transistor.

As shown in FIG. 3, the subpixel structure with two transistors (2T) andone capacitor (1C) type has been discussed for convenience ofdiscussion, but the embodiments are not limited thereto. In someembodiments, the subpixel can further include at least one transistorand/or at least one capacitor. In some embodiments, a plurality ofsubpixels can have an identical structure, or at least one or more ofthe plurality of subpixels can have a different structure from others.

FIG. 4 is a cross-sectional view illustrating the display deviceaccording to embodiments of the present disclosure.

Referring to FIG. 4, the display panel according to embodiments of thepresent disclosure can include a substrate (SUB), an overcoat layer (OC)located over the substrate, a first anode electrode (ANO1) located onthe overcoat layer, a second anode electrode (ANO2) located on theovercoat layer, a third anode electrode (ANO3) located on the overcoatlayer, a bank layer (BNK) located on the overcoat layer and the first,second and third anode electrodes (ANO1, ANO2 and ANO3), a first organiclight emitting layer (EL1) located on a part of the first anodeelectrode, a second organic light emitting layer (EL2) located on a partof the second anode electrode, a third organic light emitting layer(EL3) located on a part of the third anode electrode, and a cathodeelectrode (CAT) located on at least one of the first, second and thirdlight emitting layers and the bank layer.

The substrate (SUB) can be subdivided into areas corresponding to afirst subpixel (SP1), a second subpixel (SP2) and a third subpixel(SP3).

The first subpixel (SP1) can emit visible light of a first color, thesecond subpixel (SP2) can emit visible light of a second color, and thethird subpixel (SP3) can emit visible light of a third color. The firstsubpixel (SP1), the second subpixel (SP2) and the third subpixel (SP3)can be also defined as a first subpixel type (SP1), a second subpixeltype (SP2) and a third subpixel type (SP3), respectively. Accordingly,hereinafter, either the subpixel or the subpixel type will usedinterchangeably.

The overcoat layer (OC) can denote a layer for planarizing at least onepattern layer disposed over the substrate for forming a pixel. Theovercoat layer can include a convex area (CONV) and a concave area(CONC), which are connected to each other through an inclined area(SLO).

The convex area (CONV) can thicker than the concave area (CONC). Indefining the convex area (CONV) and the concave area (CONC), thethickness of the convex area (CONV) and the concave area (CONC) denotesa thickness of the overcoat layer. The thickness of the convex area(CONV) and the concave area (CONC) can be defined as a thickness of theovercoat layer measured between a passivation layer (PAS) disposeddirectly under the overcoat layer (OC) and an anode electrode (ANO)disposed directly on the overcoat layer (OC), in each area, and inparticular, can be defined as the thickest thickness of the overcoatlayer measured in each area except for a portion in which a contacthole, or the like is introduced.

As shown in FIG. 4, the thickness (T1) of the concave area (CONC) can besmaller than the thickness (T2) of the convex area (CONV). Accordingly,relative to the cross section of the display panel, the concave area(CONC) can be recognized as a flat area of the overcoat layer (OC), andthe convex area (CONV) can be recognized as a protruding area.

The inclined area (SLO) can be formed between the convex area (CONV) andthe concave area (CONC) due to a difference between the thicknesses ofthe convex area (CONV) and the concave area (CONC). The convex area(CONV) and the concave area (CONC) can be connected to each otherthrough the inclined area (SLO). The inclined area (SLO) can include afirst inclined surface (SLO1) surrounding the concave area (CONC) in atleast one of the first, second and third subpixel types (SP1, SP2 andSP3). The at least one of the first, second and third subpixel types(SP1, SP2 and SP3) can denote at least one type of subpixel, in whichthe type of the subpixel is classified according to a color of lightemitted from the subpixel. For example, when a display panel includes ared subpixel, a green subpixel and a blue subpixel, the display panelcan be expressed as including three types of subpixel.

The first inclined surface (SLO1) can denote an inclined surface that isan inclined area surrounding the concave area (CONC) of inclined areas(SLO) formed between the convex area (CONV) and the concave area (CONC)of the overcoat layer (OC). Accordingly, in the display panel shown inFIG. 4, the first subpixel (SP1) and the second subpixel (SP2) includesthe inclined area, and thus includes the first inclined surface (SLO1).On the other hand, the third subpixel (SP3) does not include theinclined area surrounding the concave area (CONC), and thus does notinclude the first inclined surface (SLO1).

Since the convex area (CONV) surrounds the concave area (CONC), in thecross section of the display panel, the concave area (CONC) can belocated between the convex areas (CONV).

The overcoat layer (OC) including the convex area (CONV), the concavearea (CONC) and the inclined area (SLO) can be formed through aphotolithography process using a half-tone mask.

There is no restriction to a shape of the concave area (CONC). The shapeof the concave area (CONC) may preferably be, but not limited to, apolygonal shape, such as a circle or a square, a pentagon, and anoctagon. The convex areas (CONV) can surround the concave area (CONC),and can form a side wall surrounding a side portion of the concave area(CONC) having the shape described above.

The first anode electrode (ANO1), the second anode electrode (ANO2), athird anode electrode (ANO3), formed along a surface of the overcoatlayer (OC), can be located on the overcoat layer (OC) located over thesubstrate.

The forming of the anode electrodes (ANO1, ANO2 and ANO3) along thesurface of the overcoat layer (OC) can mean that the anode electrodesare formed on the overcoat layer with a thickness that is considered tobe uniform when a thickness variation due to a tolerable processdeviation is taken into account (e.g., the anodes can follow thecontours of the surface of the overcoat layer).

Each of the first anode electrode (ANO1), the second anode electrode(ANO2) and the third anode electrode (ANO3) can be spaced apart from oneanother by a certain distance, and can transfer independently a signalto a corresponding subpixel.

As described above, the overcoat layer (OC) can include the firstinclined surface (SLO1) surrounding the concave area (CONC) in at leastone of the first, second and third subpixel types (SP1, SP2 and SP3).Accordingly, in a situation where the anode electrode is formed along asurface of the first inclined surface (SLO1) that is a part of thesurface of the overcoat layer (OC), the anode electrode can also includean inclined surface. In the present disclosure, such an inclined surfaceof the anode electrode can be referred to as a second inclined surface(SLO2).

In addition, since the anode electrodes (ANO1, ANO2 and ANO3) are formedalong the surface of the overcoat layer (OC), the second inclinedsurface (SLO2) can be a shape surrounding the anode electrode portionsformed on the concave area (CONC) of the overcoat layer (OC).

The first, second and third anode electrodes can be electricallyconnected to one another through a contact hole.

The anode electrode can be an electrode including a reflectiveelectrode. The anode electrode can include a conductive metal oxidelayer including indium tin oxide ITO and a reflective metal layerincluding silver. For example, the anode electrode can include a firstindium tin oxide ITO layer located on the overcoat layer, the reflectivemetal layer including silver located on the first indium tin oxide ITOlayer, and a second indium tin oxide ITO layer located on the reflectivemetal layer.

The anode electrodes can function as anode electrodes in the displaypanel.

The bank layer (BNK1) may include an open area (BNKO) located in thecenter area of each of the first, second and third subpixels (SP1, SP2,SP3). The open area (BNKO) of the bank denotes an open area in which thebank layer does not cover the anode electrode, and can denote an areaindicated by the OPN as shown in FIG. 4. The open area (BNKO) of thebank denotes an open area formed in the bank layer, in which the anodeelectrode is exposed by the open area (BNKO) of the bank. The organiclight emitting layer and the cathode electrode can be sequentiallydisposed on the exposed anode electrode. Accordingly, the open area(BNKO) of the bank is provided in the center area of each of thesubpixels emitting light, and thus allows the subpixels to emit thelight.

The first organic light emitting layer (EL1) can be located on a part ofthe first anode electrode (ANO1) located in the open area (BNKO) of thebank. The second organic light emitting layer (EL2) can be located on apart of the second anode electrode (ANO2) located in the open area(BNKO) of the bank. The third organic light emitting layer (EL3) can belocated on a part of the third anode electrode (ANO3) located in theopen area (BNKO) of the bank.

Since the first, second and third organic light emitting layers (EL1,EL2 and EL3) are layers discharging light when an exciton having highenergy formed from the recombination of a hole and an electron injectedthrough an anode and a cathode falls into low energy, the first, secondand third organic light emitting layers (EL1, EL2 and EL3) can belocated on the exposed anode electrodes (ANO1, ANO2, ANO3) not coveredby the open area (BNKO) of the bank. The anode electrodes (ANO1, ANO2,and ANO3) can be an anode.

The cathode electrode (CAT) can be located on the organic light emittinglayer (EL1, EL2, EL3) and the bank layer (BNK). The display panel can bea top emission type in which light emitted from the organic lightemitting layer (EL1, EL2, EL3) is emitted through the cathode electrode(CAT). Accordingly, the cathode electrode (CAT) can be a transparentelectrode with excellent transmittance to light in the visible lightregion, and the bank layer (BNK) can perform a function as a layer fordistinguishing between an opening area (OPN) and a non-opening area(NOP) of the display panel.

As described above, the display panel in the present disclosure caninclude two different types of areas, which are the opening area (OPN)and the non-opening area (NOP) subdivided by the configuration of thebank layer (BNK). The opening area (OPN) can correspond to the open area(BNKO) of the bank, and the non-opening area (NOP) can correspond to thebank layer (BNK) except for the open area (BNKO). The opening area (OPN)and the non-opening area (NOP) can be located in the active area (A/A)of the display panel.

The correspondence of an area to another area may mean a relationship inwhich the one area and the another area are considered to be the same,taking into account tolerance that may occur in the manufacturingprocess of a product.

As described above, since the anode electrode (ANO1, ANO2, ANO3), thebank layer (BNK), the organic light emitting layer (EL1, EL2, EL3) andthe cathode electrode (CAT) are located over the overcoat layer (OC),light can be emitted from the opening area (OPN) in which the anodeelectrode (ANO1, ANO2, ANO3), the organic light emitting layer (EL1,EL2, EL3) and the cathode electrode (CAT) in the open area (BNKO) of thebank layer are sequentially disposed.

The display panel according to embodiments of the present disclosure caninclude a buffer layer (BUF), a interlayer insulating film (INF), apassivation layer (PAS), a transistor (TR), a storage capacitor (C1,C2), an auxiliary electrode (AE, or may be referred to as an auxiliaryline) and a pad area.

The buffer layer (BUF) can be disposed on the substrate (SUB), and thetransistor (TR) and the storage capacitor (C1, C2), and the like can bedisposed over the buffer layer (BUF).

The interlayer insulating film (INF) can be located on a gate electrode(GATE) of the transistor (TR), an active layer (ACT), a first storagecapacitor (C1) of the storage capacitor, and a first pad electrode (P1)of the pad area.

The passivation layer (PAS) can be disposed to protect electronicelements, such as the auxiliary electrode (AE), the storage capacitor(C1, C2), the transistor (TR), and the like.

The transistor (TR) can include the activation layer (ACT), a gateinsulating film (GI), a gate electrode (GATE), a source electrode (S)and a drain electrode (D). Hereinafter, discussions are conducted on atransistor according to embodiments of the present disclosure. Typicalimplementations performed in the field of the present disclosure can beused to describe a location relationship between respective elements ofthe transistor in the present disclosure.

The activation layer (ACT) can be disposed on the buffer layer (BUF).

The gate insulating film (GI) is disposed on the activation layer (ACT),and the gate electrode (GATE) is disposed on the gate insulating film(GI). Therefore, the gate insulating film (GI) can be located betweenthe activation layer (ACT) and the gate electrode (GATE).

Each of the source electrode (S) and the drain electrode (D) can contactrespective portions of the activation layer ACT, and be disposed spacedapart from each other. The drain electrode (D) can be connected to theanode electrode (ANO) through a contact hole.

The transistor (TR) can function as a driving transistor (DRT) includedin the panel, and drive the OLED included in the panel.

As shown in FIG. 4, the storage capacitor (C1, C2) can be disposed inthe active area (A/A). The storage capacitor (C1, C2) can include afirst storage capacitor electrode (C1) disposed in an identical layer tothe gate electrode (GATE) and a second storage capacitor electrode (C2)disposed in an identical layer to the source electrode (S) and the drainelectrode (D), but the structure of the storage capacitors (C1, C2) ofthe present disclosure is not limited thereto.

In addition, the display panel according to embodiments of the presentdisclosure can include a pad area disposed in the non-active area. Aplurality of pad electrodes (P1 and P2) can be disposed in the pad area.

For example, a first pad electrode (P1) can be disposed on the pluralityof insulating films (BUF, GI) disposed in the pad area. The interlayerinsulating film (INF) can be disposed on the first pad electrode (P1), apart of the top surface of which is not covered by the first padelectrode (P1). A second pad electrode (P2) that contacts the first padelectrode (P1) can be disposed over the first pad electrode (P1) and theinterlayer insulating film (INF).

In addition, various circuit films, or the like can be electricallyconnected to the second pad electrode (P2).

FIG. 5 is a view illustrating how light emitted from any subpixel of thedisplay panel can travel according to embodiments of the presentdisclosure. The subpixel shown in FIG. 5 is a subpixel including thefirst inclined surface (SLO1), the second inclined surface (SLO2) andthe third inclined surface (SLO3)

Referring to FIG. 5, light (L) emitted from an organic light emittinglayer (EL) is emitted in various directions without directivity in aspecific direction. The organic light emitting layer (EL) can be one ofthe first organic light emitting layer (EL1), second organic lightemitting layer (EL2) and the third organic light emitting layer (EL3),and as described above, is an organic light emitting layer included inthe subpixel including the first inclined surface (SLO1), the secondinclined surface (SLO2) and the third inclined surface (SLO3). Some oflight emitted from the organic light emitting layer (EL) may be totallyreflected and travel toward third inclined surface (SLO3) of the banklayer (BNK), while traveling from a layer with a high refractive indexto a layer with a low refractive index.

The bank layer (BNK) is formed of a material with a certain range oftransmittance to light in a visible light wavelength range. Accordingly,some light emitted toward the third inclined surface (SLO3) of the banklayer (BNK) can travel through the third inclined surface (SLO3) of thebank layer (BNK), and then reach the second inclined surface (SLO2) ofthe anode electrode (ANO). The anode electrode (ANO) is also one of thefirst anode electrode (ANO1) to the third anode electrode (ANO3). Itshould be understood that the anode electrode (ANO) is an anodeelectrode included in a subpixel including the first, second and thirdinclined surfaces. In other words, the structure can utilize the threedifferent inclined surfaces from existing layers to provide three morechances to reflect light out of the device, thus improving lightextraction without increasing the thickness of the device and withoutrequiring separate reflective structures (e.g., edges of the overcoatlayer, anode electrode and bank layer can be leveraged to provideadditional functions, such as light extraction and reflection, and colorshifting).

Light having reached the second inclined surface (SLO2) of the anodeelectrode (ANO) is reflected from the second inclined surface (SLO2),and then may travel toward the third inclined surface (SLO3) of the banklayer (BNK) and travel out of the display panel. Accordingly, asdescribed above, in the display panel according to embodiments of thepresent disclosure, the second inclined surface (SLO2) of the anodeelectrode formed on the first inclined surface (SLO1) enables lightemitted from the organic light emitting layer (EL) to travel toward anupper portion of the display panel, resulting in the luminous efficiencyof the display panel being improved.

FIG. 6 is an enlarged cross-sectional view illustrating a part of thesubpixel shown in FIG. 5 according to embodiments of the presentdisclosure.

Referring to FIG. 6, an angle (θ) between the concave area (CONC) andthe first inclined surface (SLO1) is represented as θ (hereinafter,referred to as “θ”), a distance between the second inclined surface(SLO2) and the third inclined surface (SLO3) is represented as d(hereinafter, referred to as “d”), and a height of the first inclinedsurface (SLO1) is represented as h (hereinafter, referred to as “h”).According to embodiments of the present disclosure, it is possible toprovide a display panel with increased luminous efficiency by adjustingtwo or more of the θ, the d and the h. For example, the display panelaccording to embodiments of the present disclosure can have specificvalues of θ and d, or specific values of θ, d and h.

The angle (θ) between the concave area (CONC) and the first inclinedsurface (SLO1) can be greater than or equal to 27°, or 45°. As the θ hasa larger value, the second inclined surface (SLO2) can more effectivelyreflect light emitted from the organic light emitting layer (EL) formedon the anode electrode (ANO) not covered by the open area (BNKO) of thebank. There is no restriction to the upper limit of a range of the θ. Inthis situation, the possibility that cracks and breaks occur in theanode electrode (ANO) formed on the overcoat layer increases, as the θhas a larger value. Accordingly, the upper limit may be preferably lessthan or equal to 80°, 70°, or 65°. For example, the angle θ can be in arange of approximately 27° to 80°.

The d that is the distance between the second inclined surface (SLO2)and the third inclined surface (SLO3) can be defined as a distance fromthe second inclined surface (SLO2) to the third inclined surface (SLO3),measured in a parallel direction to the first area (A1) of the overcoatlayer. The d can be less than or equal to 3.2 μm, 2.6 μm or 2.0 μm. Thesmaller the d is, the greater the opening area (OPN) of the displaypanel expands. In this situation, traveling paths of reflected lightfrom reflecting by the second inclined surface (SLO2) to being extractedto outside of the display panel may reduce and thus luminous efficiencymay increase. To this end, there is no restriction to the lower limit ofthe d. The lower limit of the d may be preferably greater than or equalto 0.1 μm, 0.3 μm, or 0.5 μm. For example, the distanced can be in arange of approximately 0.1 μm to 3.2 μm.

By adjusting the d within this range, it is possible to expand anopening area and to provide a display panel with increased luminousefficiency.

The h that is the height of the first inclined surface (SLO1) denote adifference between a thickness (T1′) of the concave area (CONC) and athickness (T2′) of the convex area (CONV), which are connected by thefirst inclined surface (SLO1). The thickness (T1′) of the concave area(CONC) can be a thickness of the concave area (CONC) measured at thebeginning of the first inclined surface (SLO1). The thickness (T2′) ofthe convex area (CONV) can be a thickness of the convex area (CONV)measured at the end of the second inclined surface (SLO2).

The h can be preferably greater than or equal to 0.7 μm, 1.2 μm, 1.4 μm,or 2 μm. The larger the h is, the greater the luminous efficiencyincreases because light emitted from the organic light emitting layer(EL) is reflected effectively by the second inclined surface (SLO2). Tothis end, there is no restriction to the upper limit of the h. The upperlimit may be preferably less than or equal to 10 μm, or 5 μm. Forexample, the height h can be in a range of approximately 0.7 μm to 10μm.

As described above, by adjusting the d, the θ and the h, the displaypanel according to the present disclosure can provide increased luminousefficiency and can include the first light emitting area and the secondlight emitting area when the organic light emitting layer emits light.

FIGS. 7A and 7B show views illustrating the display panel including anopening area, a non-opening area, a first light emitting area, and asecond light emitting area according to embodiments of the presentdisclosure.

FIG. 7A shows a photomicrograph of the display panel including anopening area (OPN) and a non-opening area (NOP) having a specific shape.FIG. 7B shows a photomicrograph taken when the organic light emittinglayer (EL1, EL2, EL3) of the display panel emits light. All subpixelsshown in FIG. 7A include the first inclined surface (SLO1) to the thirdinclined surface (SLO3).

Referring to FIG. 7, the display panel according to the presentdisclosure can include a first light emitting area (LEA1) and a secondlight emitting area (LEA2), in which visible light is emitted when theorganic light emitting layer emits light, and a first non-light emittingarea (NEA1) and a second non-light emitting area (NEA2).

The second non-light emitting area (NEA2) is included in a subpixelincluding the first inclined surface (SLO1), the second inclined surface(SLO2) and the third inclined surface (SLO3). A subpixel not includingthe first inclined surface (SLO1) to the third inclined surface (SLO3)includes only the first light emitting area, but does not include thesecond light emitting area. Accordingly, all of the subpixels of thedisplay panel shown in FIG. 7 include the first inclined surface (SLO1),the second inclined surface (SLO2) and the third inclined surface(SLO3).

The first light emitting area (LEA1) can have a shape corresponding to ashape of the opening area (OPN). The correspondence of a shape of anelement to a shape of another element can mean that i) the shape of theelement is an identical shape to the another element, ii) two elementshave an identical shape, but have different sizes from each other, oriii) the shape of the element can be formed by transferring the shape ofthe another element. Accordingly, the shape of the first light emittingarea (LEA1) can mean that the shape of the opening area (OPN) issubstantially transferred by light emitted from the organic lightemitting layer (EL1, EL2, EL3) located in the opening area (OPN).

There is no restriction to a shape of the opening area (OPN). The shapeof the opening area (OPN) can preferably be, but not limited to, apolygonal shape, such as a circle or a square, a pentagon, and anoctagon. Referring to FIG. 7A, the opening area (OPN) has a shapecorresponding to the octagon.

The first light emitting area (LEA1) can have a shape corresponding tothe opening area (OPN). Referring to FIG. 7B, the first light emittingarea (LEA1) has a shape corresponding to the shape of opening area (OPN)as shown in FIG. 7A.

The second light emitting area (LEA2) does not overlap the first lightemitting area (LEA1). The second light emitting area (LEA2) can have ashape corresponding to a shape of an edge of the first light emittingarea (LEA1). As shown in FIG. 7B, the second light emitting area (LEA2)has an identical shape to the edge of the first light emitting area(LEA1), but has different size from the first light emitting area(LEA1). Therefore, it is possible to express that the second lightemitting area (LEA2) has a shape corresponding to the edge shape of thefirst light emitting area (LEA1).

The second light emitting area (LEA2) can be a closed curve having anidentical shape to the edge of the first light emitting area (LEA1). Foranother example, the second light emitting area (LEA2) can have a shapein which a part of the closed curve is disconnected. It is possible todetermine whether the second light emitting area (LEA2) is disconnected,depending on a wavelength of visible light emitted from an organic lightemitting layer included in a subpixel.

At least one subpixel can be distinguished by the first light emittingarea (LEA1). Referring to FIG. 7B, each of a plurality of second lightemitting areas (LEA2) can be spaced apart from one another by the firstnon-light emitting area (NEA1). That is, the first non-light emittingarea (NEA1) can be an area between the second light emitting areas(LEA2) in the non-opening area (NOP).

That is, the first non-light emitting area (NEA1) can be substantiallyan area in which light emitting is not performed. That is, the firstnon-light emitting area (NEA1) can correspond to a part of thenon-opening area (NOP), in which the second light emitting area (LEA2)is not formed,

A light emitting area formed in one subpixel can be divided into thefirst light emitting area (LEA1) and the second light emitting area(LEA2) by the second non-light emitting area (NEA2). The secondnon-light emitting area (NEA2) may be an area in which light emitting isnot substantially performed.

A shape of the second non-light emitting area (NEA2) may be determineddepending on the shapes of the first light emitting area (LEA1) and thesecond light emitting area (LEA2). For example, in a situation where thefirst light emitting area (LEA1) has an octagon shape, and the secondlight emitting area (LEA2) has a closed curve with the octagon shape,the second non-light emitting area (NEA2) can have the octagon shape bythe first light emitting area (LEA1) and the second light emitting area(LEA2).

Although the second non-light emitting area (NEA2) is described usingthe term of non-light emitting, it is possible for some light to bedetected in the photograph because the second non-light emitting area(NEA2) is located between the light emitting areas (LEA1 and LEA2). Inparticular, it is possible for light with colors similar to a wavelengthrange of visible light emitted in the subpixel to be detected.Accordingly, the second non-light emitting area (NEA2) can be an area inwhich light emitting is not performed at all, or it should be understoodthat the second non-light emitting area (NEA2) can be an area in whichlight less than two light emitting areas is observed.

As described above, the second light emitting area (LEA2) can beimplemented by adjusting a range of the θ, the d, or the h. Accordingly,the display panel according to embodiments of the present disclosure mayhave increased luminous efficiency and include the first light emittingarea (LEA1) and the second light emitting area (LEA2), by adjusting arange of the θ, the d, or the h. For example, the second light emittingarea (LEA2) can reflect light out of the device, which otherwise may nothave been able to escape.

It is believed that the second light emitting area (LEA2) is formed bylight traveling through paths described with reference to FIG. 5. Thesubpixel shown in FIG. 5 includes, as well as the first light emittingarea (LEA1), the second light emitting area (LEA2) formed by lightreflected from the second inclined surface (SLO2). Therefore, it ispossible to provide the display panel with increased luminousefficiency. In accordance with embodiments of the present disclosure,the overcoat layer configured with the first inclined surface (SLO1)surrounding the concave area (CONC) is included in at least one of thefirst subpixel type to the third subpixel type, and thus it is possibleto provide the display panel with enhanced luminous efficiency.

The second light emitting area (LEA2) can surround the first lightemitting area (LEA1). In other words, the second light emitting area(LEA2) can be located all around the first light emitting area (LEA1).It is believed that this is because the second light emitting area(LEA2) is formed by light reflected from the second inclined surface(SLO2) of the anode electrode (ANO) formed on the first inclined surface(SLO1) surrounding the concave area (CONC).

In addition, the second light emitting area (LEA2) can be located in thenon-opening area (NOP). As described above, since the second lightemitting area (LEA2) is formed by light reflected from the secondinclined surface (SLO2) located in the non-opening area (NOP), all orpart of the second light emitting area (LEA2) can be located on thenon-opening area (NOP).

As shown in FIG. 5, light forming the first light emitting area (LEA1)and the second light emitting area (LEA2) travels through differentpaths and different layers, and therefore corresponding colorcoordinates may be different. That is, light forming the second lightemitting area (LEA2) travels through the bank layer (BNK) in thenon-opening area (NOP), while the light forming the first light emittingarea (LEA1) does not travel through the bank layer. The bank layer (BNK)may absorb a portion of the light of a part of the wavelength of lightforming the second light emitting area (LEA2), and therefore, the lightforming the second light emitting area (LEA2) may have different colorcoordinates from the light forming the first light emitting area (LEA1).Here, the difference of the color coordinates can mean that there is adifference that can be regarded as different, taking into account atypical error caused at the time of measuring the color coordinates.

Although the second non-light emitting area (NEA2) is described usingthe term of non-light emitting, it is possible for some light to bedetected in the photograph because the second non-light emitting area(NEA2) is located between the light emitting areas (LEA1 and LEA2). Inparticular, it is possible for light with colors similar to a wavelengthrange of visible light emitted in the subpixel to be detected.Accordingly, the second non-light emitting area (NEA2) can be an area inwhich light emitting is not performed at all, or it should be understoodthat the second non-light emitting area (NEA2) can be an area in whichlight less than two light emitting areas is observed.

As shown in FIG. 7B, a plurality of the first light emitting areas andthe second light emitting areas can be formed according to the number ofsubpixel areas included in the display panel, for example, the firstsubpixel, the second subpixel, the third subpixel, etc. Thus, it shouldbe understood that the second light emitting area adjacent to the firstlight emitting area is a light emitting area included in an identicalsubpixel area, and denotes the second light emitting area adjacent tothe first light emitting area of a plurality of the second lightemitting areas. This is because a first light emitting area and a secondlight emitting area adjacent to the first light emitting area arelocated in one subpixel area, and a light emitting area is formed bylight emitted from an identical organic light emitting layer.

FIG. 8 is a view illustrating that light emitted from a subpixel of thedisplay panel travels according to embodiments of the presentdisclosure. Unlike the subpixel shown in FIGS. 5 and 6, the subpixelshown in FIG. 8 does not include the first inclined surface (SLO1) andthe second inclined surface (SLO2). Accordingly, unlike the subpixelsshown in FIGS. 5 and 6, the subpixel includes only the first lightemitting area (LEA1) without the second light emitting area (LEA2)formed.

As described above, the subpixel having the structure shown in FIG. 5includes the first light emitting area (LEA1) and the second lightemitting area (LEA2), and light emitted from the second light emittingarea (LEA2) has different color coordinates from light emitted from thefirst light emitting area (LEA1). Such a difference in the colorcoordinates results from a difference between a traveling path of lightemitted from the first light emitting area (LEA1) and a traveling pathof light emitted from the second light emitting area (LEA2). That is, adifference in traveling paths of the second light emitting area (LEA2)and the first light emitting area (LEA1) results in a variation in thecolor coordinates (e.g., a color shift).

Inventors of the present disclosure have observed that the variation ofthe color coordinates is affected by a wavelength range of light emittedfrom an organic light emitting layer. Accordingly, to preventdeterioration of the display panel due to the variation of the colorcoordinate, in the display including a first subpixel to a thirdsubpixel (or, a first subpixel type to a third subpixel type) emitting afirst color to a third color, i) at least one type of subpixel caninclude the first inclined surface (SLO1), ii) at least one of a firstsubpixel type and a second subpixel type can include the first inclinedsurface (SLO1), and iii) at least one of a first subpixel type and asecond subpixel type can include the first inclined surface (SLO1) and athird subpixel type can be a type without the first inclined surface(SLO1). A subpixel including the first inclined surface (SLO1) can havea structure shown in FIG. 5, and a subpixel not including the firstinclined surface (SLO1) can have a structure shown in FIG. 8. Forexample, the mixed subpixel types can help hide or avoid any detectablecolor shifts or undesirable color shifts.

The subpixel having structure shown in FIG. 8 can be a subpixel emittinglight in a wavelength range in which a degree of color variationresulted from the forming of the second light emitting area is large.

For example, visible light of a first color emitted from the firstsubpixel can be red visible light, visible light of a second coloremitted from the second subpixel can be green visible light, and visiblelight of a third color emitted from the third subpixel can be bluevisible light.

The visible light of the red color can denote visible light typicallyrecognized as red when viewed through the naked eye or a photographingdevice, for example, visible light having a wavelength range of 595 nmto 740 nm. The visible light of the green color can denote visible lighttypically recognized as green when viewed through the naked eye or aphotographing device, for example, visible light having a wavelengthrange of 495 nm to 595 nm. The visible light of the blue color candenote visible light typically recognized as blue when viewed throughthe naked eye or a photographing device, for example, visible lighthaving a wavelength range of 450 nm to 495 nm.

As described above, in the display panel according to embodiments of thepresent disclosure, the first inclined surface can be absent from asubpixel emitting a color resulting in a large color variation, but canbe included in a subpixel emitting a color resulting in a small colorvariation, resulted from the forming of the second light emitting area.Thus, it is possible to provide the display panel with enhanced luminousefficiency, low quality deterioration according to angles of view, andan excellent color gamut.

In addition, the display panel according to embodiments of the presentdisclosure may be configured to adjust the θ, the d, and the h describedabove according to a color emitted from a subpixel.

In the display panel according to embodiments of the present disclosure,the overcoat layer may include the first inclined surface in at leasttwo of the first subpixel type to the third subpixel type. An angle ofthe first inclined surface included in each of the first, second andthird subpixel types can be different from one another. A distancebetween the second inclined surface and the third inclined surface ineach of the first, second and third subpixel types can be different fromone another.

In addition, in a situation where the overcoat layer includes the firstinclined surface in at least two of the first subpixel type to the thirdsubpixel type, a height of the first inclined surface included in eachof the first, second and third subpixel types can be different from oneanother. Each type of subpixel can refer to a subpixel type that emits adifferent color from one another when a subpixel that emits light of acolor is expressed as one type of subpixel.

Referring to FIG. 4, since the first subpixel (SP1) and the secondsubpixel (SP2) include the first inclined surface (SLO1), therefore, thedisplay panel includes at least two of the first, second and thirdsubpixel types. In addition, since each of the first subpixel (SP1) andthe second subpixel (SP2) emits a different color, an angle (θ) of afirst inclined surface included in the first subpixel (SP1) can beadjusted differently from an angle (θ) of a first inclined surfaceincluded in the second subpixel (SP2), taking into accountcharacteristics of light of the different color. In addition, a distance(d) between the second inclined surface and the third inclined surfacecan be also adjusted differently for enabling a corresponding valuemeasured in the first subpixel (SP1) to be different from acorresponding value measured in the second subpixel (SP2). A height (h)of the first inclined surface can be adjusted differently for enabling aheight of a first inclined surface included in the first subpixel (SP1)to be different from a height of a first inclined surface included inthe second subpixel (SP2). As described above, in the situation wherethe θ, the d and the h are adjusted differently depending oncharacteristics of the color of light emitted from each subpixel, it ispossible to maximize light extraction efficiency (e.g., different colorsmay perform better with different settings for the θ, the d and the h,based on the corresponding wavelengths).

FIG. 9 is a cross-sectional view illustrating the display deviceaccording to embodiments of the present disclosure.

Referring to FIG. 9, the organic light emitting layer (EL) can bedisposed on parts of the anode electrode (ANO) that are not covered bythe open area (BNKO) of the bank layer and the bank layer (BNK), forexample, extending from a portion on the anode electrode (ANO) that isnot covered by the open area (BNKO) of the bank layer to a portion onthe bank layer (BNK). The cathode electrode (CAT) can be located on theorganic light emitting layer (EL). FIG. 9 shows that the organic lightemitting layer (EL) covers the whole top surface of the bank layer(BNK), but embodiments of the present disclosure are not limitedthereto. The organic light emitting layer (EL) can be disposed to coverthe open area (BNKO) of the bank layer and a part of the top surface ofthe bank layer (BNK).

In the situation where the organic light emitting layer (EL) is disposedacross both the opening area (OPN) (in which the bank layer (BNK) is notdisposed) and parts of the non-opening area (NOP) (in which the banklayer (BNK) is disposed), it is possible to maximize an area of theorganic light emitting layer (EL) in which light emitting is performed.In the situation where the organic light emitting layer (EL) is disposedin only the opening area (OPN) (e.g., not on parts of the bank layer),due to limitations in process, the organic light emitting layer (EL) maynot be formed in an edge portion of the opening area (OPN) or may beincompletely formed. However as described above, when the organic lightemitting layer (EL) is disposed on parts of the bank layer (BNK) aswell, it is possible to overcome some problems with limitations inprocess.

FIG. 10 is an enlarged cross-sectional view illustrating a part of thedisplay device shown in FIG. 9 according to embodiments of the presentdisclosure.

Referring to FIG. 10, a thickness (t1) of the organic light emittinglayer (EL) disposed on the anode electrode (ANO) is larger than athickness (t2) of the organic light emitting layer (EL) disposed on thethird inclined surface (SLO3) of the bank layer (BNK).

The difference in the thicknesses of the organic light emitting layercan be caused by the third inclined surface (SLO3) of the bank layer(BNK). The organic light emitting layer (EL) can be formed by a thermalevaporation process, which is a physical vapor deposition technique.When the thermal evaporation process is used on the inclined surface,such as the third inclined surface (SLO3), the thickness of thedeposited layer may reduce due to characteristics of the thermaldeposition process,

In a situation where a portion of the organic light emitting layerbecomes thin, the density of carriers may increase at an electrodeadjacent to the organic light emitting layer with the thin thickness andresult in the organic light emitting layer being deteriorated. However,it is possible to prevent such problems in the display panel accordingto embodiments of the present disclosure because the bank layer (BNK) islocated between the anode electrode (ANO) and the organic light emittinglayer (EL), in a portion in which the organic light emitting layer (EL)has the thinned thickness (t2), as shown in FIG. 10. In other words, thebank layer can help separate the thin portion of the organic lightemitting layer (EL) to be just far enough away (e.g., distance “d”) fromthe anode so that the density of carriers at the thin part of theorganic light emitting layer (EL) does not unduly increase and preventsthe organic light emitting layer from being prematurely deteriorated.

The following Table 1 shows the observation on light emitting of thesecond light emitting area according to the variations of the θ, the dand the h in a subpixel including the first inclined surface. Thesubpixels used for observing whether the second light emitting area isformed in the Table 1 have the structure shown in FIG. 9.

TABLE l Whether the second light θ(°) h(μm) d(μm) emitting area isformed Comparative 8 0.6 2 X example 1 Comparative 25 1.7 2 X example 2Comparative 25.8 1.7 2 X example 3 Embodiment 1. 45 1.4 2 ◯ Embodiment2. 60 2 2 ◯ Embodiment 3. 60 2.04 2 ◯

Referring to the Table, 1, it is noted that the second light emittingarea is formed when i) the θ is greater than or equal to 27°, 35°, or45°, ii) the h is greater than or equal to 0.7 μm, 1.0 μm, or 1.4 μm,and iii) the d is less than or equal to 3.2 μm. Accordingly, the secondlight emitting area is formed in subpixels including the first inclinedsurface, and therefore, it is expected to exhibit excellent luminousefficiency.

The following Table 2 shows luminous efficiency, degradation of displayquality of images according to angles of view, and a color gamut.

TABLE 2 Comparative Embodi- Embodi- Embodi- example 4 ment 4. ment 5.ment 6. Color Rx 0.685 0.685 0.685 0.686 Gx 0.232 0.232 0.250 0.255 By0.051 0.051 0.055 0.055 Efficiency W 39.5 39.5 41.5 41.7 (cd/A) R 54.454.1 54.4 53.5 G 133 133 136.5 139.7 B 4.7 4.7 5.4 5.4 Viewing Δu‘v’0.027 0.024 0.023 0.0 Angle (Typ.) (θ: JND 15 14 12 12 0~60°) (White)Color DCI-P3 100 100 100 100 gamut (%)

The Embodiments 4 to 6 and the Comparative example 4 are display panelsincluding three types of subpixel, such as, a red subpixel, a greensubpixel, and a blue subpixel. In Comparative example 4, all three typesof subpixel do not include the first inclined surface, and each subpixelhas a structure similar to that shown in FIG. 8. In the Embodiment 4,only the red subpixel includes the first inclined surface. In theEmbodiment 5, only the green subpixel includes the first inclinedsurface. In the Embodiment 6, the red and green subpixels include thefirst inclined surface. In particular, the Embodiment 5 has thestructure of FIG. 4, and the Embodiments 4 and 5 are the same as theEmbodiment 6, except that only one type of subpixel has the firstinclined surface.

The deterioration of display quality of images according to angles ofview shown in the Table 2 is illustrated in FIGS. 11 and 12. FIGS. 11(a)and 12(a) relate to the display panel of the Comparative example 4.FIGS. 11(b) and 12(b) relate to the Embodiment 4. FIGS. 11(c) and 12(c)relate to the Embodiment 5. FIGS. 11(d) and 12(d) relate to theEmbodiment 6.

Referring to the Table 2 and FIGS. 11 and 12, a display panel havingconfigurations of the Embodiments 4 to 6, in which at least one subpixelof the red subpixel and the green subpixel includes the first inclinedsurface, and the blue subpixel does not include the first inclinedsurface has enhanced luminous efficiency and low degradation of displayquality of images according to angles of view, compared with a displaypanel having configurations of the Comparative example 4 in which allthe subpixels do not include the first inclined surface.

Although embodiments of the present disclosure has been described forillustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims. Although the example embodiments have beendescribed for illustrative purposes, a person skilled in the art willappreciate that various modifications and applications are possiblewithout departing from the essential characteristics of the presentdisclosure. For example, the specific components of the exampleembodiments can be variously modified. The various embodiments describedabove can be combined to provide further embodiments. These and otherchanges can be made to the embodiments in light of the above-detaileddescription. In general, in the following claims, the terms used shouldnot be construed to limit the claims to the specific embodimentsdisclosed in the specification and the claims, but should be construedto include all possible embodiments along with the full scope ofequivalents to which such claims are entitled. Accordingly, the claimsare not limited by the disclosure.

What is claimed is:
 1. A display panel comprising: a substrate includingfirst, second and third subpixels; an overcoat layer including a firstinclined surface in at least one of the first, second and thirdsubpixels; first, second and third anode electrodes corresponding to thefirst, second and third subpixels, respectively, wherein at least one ofthe first, second and third anode electrodes includes a second inclinedsurface overlapping with the first inclined surface of the overcoatlayer; first, second and third organic light emitting layers disposed onthe first, second and third anode electrodes, respectively; and a banklayer disposed on the overcoat layer, the bank layer including a thirdinclined surface overlapping with both the first and second inclinedsurfaces of the overcoat layer and the at least one of the first, secondand third anode electrodes, wherein at least one of the first, secondand third inclined surfaces is configured to reflect light emitted froma corresponding one of the first, second and third organic lightemitting layers, wherein a distance between the second inclined surfaceof the at least one of the first, second and third anode electrodes andthe third inclined surface of the bank layer is in a range ofapproximately 0.1 μm to 3.2 μm, the distance being along a directionthat is parallel to a lowermost surface of the bank layer in acorresponding subpixel among the first, second and third subpixels,wherein a height of the first inclined surface of the overcoat layer isin a range of approximately 0.7 μm to 10 μm, the height being equal to adifference in height between two different upper surfaces of theovercoat layer in the corresponding subpixel along a direction that isperpendicular to the two different upper surfaces of the overcoat layer,and wherein a corresponding light emitting layer among the first, secondand third organic light emitting layers in the corresponding subpixelincludes a thick light emitting layer portion disposed in a center ofthe corresponding subpixel and a thin light emitting layer portiondisposed on the third inclined surface of the bank layer, the thin lightemitting layer portion being thinner than the thick light emittingportion.
 2. The display panel according to claim 1, wherein an anglebetween the first inclined surface of the overcoat layer and animaginary line overlapping with and parallel to a lower surface of thecorresponding one of the first, second and third organic light emittinglayers is in a range of approximately 27° to 80°.
 3. The display panelaccording to claim 1, wherein an interface between the bank layer andone of the first, second and third anode electrodes is configured toreflect light emitted from the corresponding one of the first, secondand third organic light emitting layers out of the display panel, orwherein an interface between one of the first, second and third anodeelectrodes and the overcoat layer is configured to reflect light emittedfrom the corresponding one of the first, second and third organic lightemitting layers out of the display panel to generate color shifted lightand reflect the color shifted light out of the display panel.
 4. Thedisplay panel according to claim 1, wherein an interface between thebank layer and one of the first, second and third anode electrodes isconfigured to shift a color of light emitted from the corresponding oneof the first, second and third organic light emitting layers to generatecolor shifted light, or wherein an interface between one of the first,second and third anode electrodes and the overcoat layer is configuredto shift a color of light emitted from the corresponding one of thefirst, second and third organic light emitting layers to generate colorshifted light.
 5. The display panel according to claim 1, wherein aportion of the bank layer is disposed between a portion of at least oneof the first, second and third organic light emitting layers and thefirst and second inclined surfaces.
 6. The display panel according toclaim 1, wherein at least a portion of one of the first, second andthird organic light emitting layers overlaps with the first, second andthird inclined surfaces.
 7. The display panel according to claim 1,wherein the overcoat layer includes the first inclined surface in atleast two of the first, second and third subpixels, and wherein thefirst inclined surface of the overcoat layer is absent from one of thefirst, second and third subpixels.
 8. The display panel according toclaim 1, wherein the display panel includes an opening areacorresponding to an open area of the bank layer and a non-opening areacorresponding to a remaining area except for the open area of the banklayer, and wherein the at least one of the first, second and thirdsubpixels having the first inclined surface, further includes: a firstlight emitting area configured to emit visual light from a correspondingorganic light emitting layer and having a shape corresponding to a shapeof the opening area; a second light emitting area configured to reflecta portion of the visual light emitted from the corresponding organiclight emitting layer, the second light emitting area surrounding thefirst light emitting area without overlapping the first light emittingarea, and having a shape corresponding to a shape of an edge of thefirst light emitting area; a first non-light emitting area locatedoutside of the second light emitting area; and a second non-lightemitting area located between the first light emitting area and thesecond light emitting area.
 9. The display panel according to claim 8,wherein the second light emitting area is located in the non-openingarea.
 10. The display panel according to claim 8, wherein the secondlight emitting area corresponds to an interface between the bank layerand one of the first, second and third anode electrodes or an interfacebetween one of the first, second and third anode electrodes and theovercoat layer.
 11. The display panel according to claim 8, whereincolor coordinates of visible light emitted from the first light emittingarea is different from color coordinates of visible light emitted fromthe second light emitting area adjacent to the first light emittingarea, and wherein the visible light emitted from the first lightemitting area and the visible light emitted from the second lightemitting area both based on light emitted from the corresponding organiclight emitting layer.
 12. The display panel according to claim 1,wherein a portion of at least one of the first, second and third organiclight emitting layers overlapping with a corresponding anode electrodeis thicker than another portion of the at least one of the first, secondand third organic light emitting layers overlapping with the thirdinclined surface of the bank layer.
 13. The display panel according toclaim 1, wherein a portion of the bank layer disposed between the thirdinclined surface of the bank layer and the second inclined surface ofthe at least one of the first, second and third anode electrodes has athickness equal to the distance between the second inclined surface ofthe at least one of the first, second and third anode electrodes and thethird inclined surface, and the thickness of the portion of the banklayer is greater than a thickness of the thin light emitting layerportion disposed on the third inclined surface of the bank layer. 14.The display panel according to claim 13, wherein the height of the firstinclined surface of the overcoat layer is greater than the distancebetween the second inclined surface of the at least one of the first,second and third anode electrodes and the third inclined surface of thebank layer, and the distance between the second inclined surface of theat least one of the first, second and third anode electrodes and thethird inclined surface of the bank layer is greater than the thicknessof the thin light emitting layer portion disposed on the third inclinedsurface of the bank layer.
 15. A display panel comprising: a substrateincluding first, second and third subpixels; an overcoat layer includinga first inclined surface in each of the first, second and thirdsubpixels; first, second and third anode electrodes corresponding to thefirst, second and third subpixels, respectively, wherein each of thefirst and second anode electrodes includes a second inclined surfaceoverlapping with the first inclined surface of the overcoat layer;first, second and third organic light emitting layers disposed on thefirst, second and third anode electrodes, respectively; and a bank layerdisposed on the overcoat layer, the bank layer including a thirdinclined surface overlapping with both the first and second inclinedsurfaces of the overcoat layer and the at least one of the first, secondand third anode electrodes, wherein at least one of the first, secondand third inclined surfaces is configured to reflect light emitted froma corresponding one of the first, second and third organic lightemitting layers, and wherein a maximum thickness of the bank layer alonga perpendicular direction that is perpendicular to an uppermost surfaceof the bank layer in an area between the third inclined surface in thethird subpixel and a top surface of the third anode electrode is greaterthan both a maximum thickness of the bank layer along the perpendiculardirection in an area between the third inclined surface in the firstsubpixel and the second inclined surface of the first anode electrode,and a maximum thickness of the bank layer along the perpendiculardirection in an area between the third inclined surface in the secondsubpixel and the second inclined surface of the second anode electrode.16. The display panel according to claim 15, further comprising: a firstcontact hole in the overcoat layer corresponding to the first subpixel;a second contact hole in the overcoat layer corresponding to the secondsubpixel; and a third contact hole in the overcoat layer correspondingto the third subpixel, wherein the overcoat layer has a first thicknessin areas overlapping with the first and second organic light emittinglayers, and a second thickness in areas outside of the first and secondorganic light emitting layers adjacent to the first and second contactholes, respectively, wherein the bank layer has a third thickness in anarea overlapping with the third contact hole in the overcoat layer, andwherein the third thickness is greater than the second thickness, andthe second thickness is greater than the first thickness.
 17. Thedisplay panel according to claim 15, wherein the first, second and thirdinclined surfaces in the first and second subpixels are parallel to eachother, and wherein the overcoat layer and the third anode electrode areflat in an area overlapping with the third inclined surface in the thirdsubpixel.
 18. The display panel according to claim 15, furthercomprising: a first light emitting area and a second light emitting areain the first subpixel; a first light emitting area and a second lightemitting area in second subpixel; and a first light emitting area in thethird subpixel, wherein the first light emitting areas in the first,second and third subpixels overlap with the first, second and thirdorganic light emitting layers, respectively, and wherein the secondlight emitting areas in the first and second subpixels overlap with thefirst, second and third inclined surfaces in the first and secondsubpixels, respectively.
 19. The display panel according to claim 18,wherein the second light emitting area in the first subpixel emits adifferent color than the first light emitting area in the firstsubpixel.
 20. A display device comprising: the display panel of claim15; and a driving circuit configured to drive the display panel, thedriving circuit including a data driver for driving a plurality of datalines and a gate driver for driving a plurality of gate lines.